ESCHERICHIA COLI CARRYING CEPHALOSPORIN (BLA) AND COLISTIN (MCR) RESISTANCE GENES ISOLATED FROM BROILERS AND PIGS IN THAILAND

Akira Fukuda1, Masaru Usui1, Chie Tagaki1, Nop Sukpanyatham2 and Yutaka Tamura1

Abstract

Spread of transferable mobile genetic elements (MGEs)-mediated antimicrobial resistance in human and veterinary medicine, especially of important antimicrobials in human medicine, is of global concern. Cephalosporin- and colistin-resistant Escherichia coli isolates and their MGEs-mediated resistance genes (bla and mcr) in broilers and pigs in Thailand were investigated using fecal samples (n = 45) from 4 broiler farms and 5 pig farms (5 fecal samples per farm) during 2014 - 2015. Broiler and pig farm samples were 60 and 90% resistant to cephalosporin respectively. Among cefotaxime-resistant E. coli isolates (n = 99), blaTEM was the most predominant (74%), followed by blaCMY-2 (45%), blaCTX-M-55 (32%), blaCTX-M-14 (29%), and blaSHV (2%); 73% of isolates harbored multiple gene types. Among mcr-positive E. coli isolates (n = 15) from broiler and pig farms, mcr-1, mcr-2, mcr-3, and mcr-2 + mcr-3 were present in 33, 7, 53, and 7% of the samples; except for one isolate, the remainings were also resistant to cefotaxime. Five bla- and mcr-positive isolates exhibited co-transfer of the genes in conjugation experiments. To the best of our knowledge, this is the first study to report mcr-2-positive isolates in a non-European country.